Films of gmercap to propyltri methoxysilane are prepared by hydrolysis, condensation and curing at 80 oC. The optical indices, n, k and the thickness d are calculated using the ellipsometry technique.Aprogramme is developed to fit a wide set of ellipsometric and data in the visible optical region 400 nm < ë < 600 nm. An increase in the optical absorption k is detected for the lower concentration ofMPTMS attributed to light absorption from the pores.Centro de Investigación y Desarrollo en Tecnología de PinturasInstituto de Investigaciones Fisicoquímicas Teóricas y Aplicada
